Add is_chromecast to GN build.

net/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/module_args/v8.gni")
 import("//testing/test.gni")
 import("//third_party/icu/config.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 # TODO(cjhopman): //build/config/android/rules.gni also imports grit_rule.gni.
 # Currently, that file can't be imported multiple times.  Make this always
 # imported when http://crbug.com/393704 is fixed.
 if (!is_android) {
   import("//tools/grit/grit_rule.gni")
 }
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
 } else if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
 }
 
 # The list of net files is kept in net.gypi. Read it.
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("net.gypi") ],
                           "scope",
                           [ "net.gypi" ])
 
-# Disable Kerberos on ChromeOS, Android and iOS, at least for now. It needs
-# configuration (krb5.conf and so on).
-use_kerberos = !is_chromeos && !is_android && !is_ios
+# Disable Kerberos on ChromeOS, Android, iOS, and Chromecast, at least for now.
+# It needs configuration (krb5.conf and so on).
+use_kerberos = !is_chromeos && !is_android && !is_ios && !is_chromecast
 
 # The way the cache uses mmap() is inefficient on some Android devices. If
 # this flag is set, we hackily avoid using mmap() in the disk cache. We are
 # pretty confident that mmap-ing the index would not hurt any existing x86
 # android devices, but we cannot be so sure about the variety of ARM devices.
 # So enable it for x86 only for now.
 posix_avoid_mmap = is_android && current_cpu != "x86"
 
 # WebSockets and socket stream code are used everywhere except iOS.
 enable_websockets = !is_ios
@@ skipping 936 matching lines @@
       sources = [
         "tools/net_watcher/net_watcher.cc",
       ]
       deps = [
         ":net",
         ":net_with_v8",
         "//base",
         "//build/config/sanitizers:deps",
       ]
 
-      if (is_desktop_linux) {
+      if (is_desktop_linux && use_gconf) {
         configs += [
           "//build/config/linux:gconf",
           "//build/config/linux:glib",
         ]
         deps += [ "//build/linux:gio" ]
       }
     }
   }
 
   executable("run_testserver") {
@@ skipping 665 matching lines @@
   if (enable_websockets) {
     sources += [ "websockets/websocket_frame_perftest.cc" ]
   }
 
   if (use_v8_in_net) {
     deps += [ ":net_with_v8" ]
   } else {
     sources -= [ "proxy/proxy_resolver_perftest.cc" ]
   }
 }